The unix library makes many Unix
system calls and system-related library functions available to
Objective Caml programs. This chapter describes briefly the functions
provided. Refer to sections 2 and 3 of the Unix manual for more
details on the behavior of these functions.

Not all functions are provided by all Unix variants. If some functions
are not available, they will raise Invalid_arg when called.

Programs that use the unix library must be linked as follows:

ocamlc other options unix.cma other files
ocamlopt other options unix.cmxa other files

A fairly complete emulation of the Unix system calls is provided in
the Windows version of Objective Caml. The end of this chapter gives
more information on the functions that are not supported under Windows.

The Cygwin port of Objective Caml fully implements all functions from
the Unix module. The native Win32 ports implement a subset of them.
Below is a list of the functions that are not implemented, or only
partially implemented, by the Win32 ports. Functions not mentioned are
fully implemented and behave as described previously in this chapter.

Functions

Comment

fork

not implemented, use create_process or threads

wait

not implemented, use waitpid

waitpid

can only wait for a given PID, not any child process

getppid

not implemented (meaningless under Windows)

nice

not implemented

in_channel_of_descr

does not work on sockets under Windows
95, 98, ME; works fine under NT, 2000, XP

out_channel_of_descr

ditto

truncate, ftruncate

not implemented

lstat, fstat

not implemented

link, symlink, readlink

not implemented (no links under
Windows)

fchmod

not implemented

chown, fchown

not implemented (make no sense on a DOS
file system)

umask

not implemented

set_nonblock, clear_nonblock

implemented as dummy
functions; use threads instead of non-blocking I/O

rewinddir

not implemented; re-open the directory instead

mkfifo

not implemented

select

implemented, but works only for sockets; use threads
if you need to wait on other kinds of file descriptors